According to my fender data tag, the wagon was scheduled 7/19/65 - pretty late in the model year! So quite possible it was a running change to use 3 bolts rather than 2 studs'/nuts and one bolt.
You might be right Don!
That stud is exactly the same as the one holding the starter. It might have been cheaper just going one partnumber on a bolt then one bolt, two studs, two washers and two nuts!!
